1. Field of the Disclosure
Aspects of the present invention generally relate to an image processing method and an image processing apparatus to print images on a printing medium.
2. Description of the Related Art
There has conventionally been known a technique to detect defective printing elements, by printing a pattern for detecting defective printing elements between printing of images and reading the pattern using a reading unit. On the other hand, if a small scratch on the printing medium, foreign matter, or the like, is included in this pattern, the image defect at that portion may be erroneously recognized as being due to a printing element failure, and the printing element may be determined to have failed even though a printing element failure has not actually occurred. Japanese Patent Laid-Open No. 2006-198793 describes preventing erroneously detecting scratches on the printing medium and so forth as being printing trouble due to a failure of the printing element, by making the pattern for detecting failure of the printing element sufficiently longer than a scratch which might be formed.
On the other hand, there are conceivably cases where foreign matter which has got into the conveyance path of the printing medium, or a protrusion created on a conveying member, coming into contact with the printing medium being conveyed, thereby consecutively scratching the printing medium and causing long streaks in the printed image. In such a case, making the pattern for detecting failure of the printing element longer, as described in Japanese Patent Laid-Open No. 2006-198793, may result in an erroneous determination that the consecutive streak formed on the printing image due to the scratch is due to failure of the printing element. Similarly, foreign matter of the like adhering to a scanning region of a sensor of a scanner or the like which scans and reads the test pattern may erroneously determine that there is a consecutive streak at the corresponding region, and that this is due to failure of the printing element corresponding to the position of the streak. Once erroneous determination is made that the printing element has failed, complementation printing processing is performed so that the printing element, which has not failed but has been erroneously determined to have failed, is not used. This unnecessary complementation printing results in an inferior image.